Motor fuel composition effective for minimizing the formation of carburetor deposits



United States Patent 2,956,869 Moron FUEL COMPOSITION EFFECTIVE FOR MINIMIZING THE FORMATION OF CARBURE- TOR DEPOSITS Richard J. De Gray, Shaker Heights, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Filed Apr. 21, 1958, Ser. No. 729,502 2 Claims. (Cl. 44--63) tor fuels, such as antioxidants, stabilizers, dyes, and thelike.

It is well known in the art presently that harmful deposits accumulate in the carburetors of motor vehicles from contaminated intake air which the carburetors must breathe in by tremendous volumes for engine operation. This troublesome condition is particularly prevalent among cars operated today in urban communities, since the major contributor to this responsible contamination in the air is believed to be the combustion products exhausted from the large population of other cars operating in the same immediate area. The condition is, of course, aggravated by any blowby fumes from the operation of the cars own engine or by any other underhood fumes generated by the cars engine in addition to any industrial fumes present in the air which the carburetor breathes. These sources of contamination are additive in nature and may cause the rapid buildup of deposits on the carburetor of the engine.

These deposits manifest themselves by causing rough idling of the engine and in many cases the occurrence of frequent stalling. Although the motor fuel itself is not responsible for these effects, it offers the most effective and economical agency for introducing a material which may remove carburetor deposits during normal vehicle operation.

It therefore is the principal aim of this invention to provide a detergent motor fuel which will minimize the formation of such deposits in the carburetor of a sparkignited internal combustion engine. In accordance with this objective, a combination of a boron compound and a trialkyl phosphite compound has been found which exhibits a synergistic effect in offering a remedy for this undesirable condition. Furthermore, due to the inclusion of these boron and phosphorus-containing compounds in the motor fuel of this invention, various important ancillary benefits are derived by their utilization in automotive engines as is well recognized in the present art.

Patent No. 2,741,548, issued to my associates and assigned to my assignee, describes certain boron compounds for incorporation in motor fuels. Included among the compounds disclosed in that patent are compounds from the following formula:

carburetors.

2 wherein X=H or The phosphorus compounds contemplated for this invention are the organic phosphites of the general formula:

O-Ri

P-O-Rg O-Ra well known to the art and are commercially available so that further information as to their preparation is unnecssary here. a

Neither the trialkyl phosphite compounds nor the boron compounds set forth above, when used separately in gasoline, demonstrate any appreciable detergency action for It is therefore particularly surprising and unexpected that when these compounds are addedvtogether they coact to offer a significant effect in preventing the formation of deposits in the carburetor of an automotive engine. Moreover, it has been found that all phosphorus compounds do not show this effect with a boron-containing gasoline so that various phosphate compounds when tested with boron compounds in gasoline demonstrate no beneficial effect on' detergency. Furthermore, many phosphorus compounds actually demonstrate antagonistic effects when added to boron compounds of this invention. For example, dialkyl acid phosphites when added to a boron-containing gasoline reduce any detergency which may be inherent in the gasoline.

The synergistic effect described for the desired combination of compounds of this invention may be gained from the use of small percentages by weight of these compounds in gasoline. The boron compound may be used in amounts to provide from 0.002 to 0.01% boron to the gasolines but preferably in amounts to provide from 0.004 to 0.008% boron, and the trialkyl phosphite compound may be used in the range from 0.005 to 0.1% by weight, but preferably from 0.025 to 0.05% by weight.

A better understanding of the effectiveness of this combination of compounds will be gained from the folinvention as compared with the base fuel without such,

compounds. In this test a contamination system was developed to simulate the conditions which contribute to carburetor deposits in the urban operation of motor vehicles. 'The system comprises the operation of a slave engine and a test engine. The exhaust gases from one bank of the slave engine (four cylinders) is metered to the crankcase of the test engine at a rate of 1.5 cubic feet per minute. All gases from the crankcase of the test engine are passed to the air intake of the carburetor of the test engine including, therefore, the exhaust gases from the slave engine and the blowby fumes of the test engine. The 1.5 cubic feet per minute rate of exhaust gases from the slave engine under these conditions constitutes approximately 8% of the total air intake of the test en Patented Oct. 18, 1960 gine at idle manifold vacuum and speed. The operating conditions for the two engines are as follows:

The test cycle was 2 hours in time, which included four acceleration periods conducted on the unloaded test engine spaced at /2 hour intervals, the first acceleration period being 30 minutes after the test cycle was commenced. During each acceleration period the throttle was moved quickly to a wide open position and then quickly closed again to an idle position five separate times to permit a surge of carburetted gasoline to come into contact with the carburetor parts. The carburetor at the start of each test was in spotless condition. All experimental conditions were the same for the test cycles except for the gasoline.

The base fuel in each test was the same and had the following composition and specifications:

At the end of each test the carburetor was removed and disassembled and a numerical rating was assigned for amount of deposits and discoloration by a number of observers rating independently and uninformed of the gasoline they were rating. The rating assigned was basedon a standardized scale ranging from 100 to 0, wherein 100 would be a rating of a perfectly clean carburetor throttle plate and barrel, and rating would represent a throttle plate and barrel loaded with deposits.

The results below represent the average rating by the observers:

Improvement Addltlve-l-Base Fuel Rating Over Base Fuel None 42 Boron Compound at 0.004% B by wt. 55 13 Tri-octyl phosphite at 0.028% by wt. 35 -7 Boron Compound at 0.004% B-l-Tri-oetyl phosphite at 0.028% 75 +33 The boron compound in the above example was added to the gasoline as an admixture of 2-methyl pentanediol-2,4 hydrogen borate and 75% bis-(2-methyl pentanediol2,4) diborate.

As may be readily seen from the table of results above, the boron compound and the trialkyl phosphite coact significantly in minimizing the formation of carburetor deposits. The expected improvement in the above example by adding the independent effects of the additives would be 6.0 unitsof improvement compared to 33 units of improvement actually observed.

I claim:

1. A gasoline containing 0.005 to 0.1% by weight of an organic phosphite of the formula:

O-Ra

wherein R R and R are selected from the group consisting of the same and different alkyl radicals containing 6 to 10 carbon atoms and a boron compound of the formula:

H B-OX (3-0 H \CH:

wherein X is selected from the group consisting of H and H0: O-( j and mixtures of the same in an amount sufiicient to provide 0.004 to 0.008% by weight boron to said gasoline.

References Cited in the file of this patent UNITED STATES PATENTS 2,261,227 Cloud Nov. 4, 1941 2,405,560 Campbell Aug. 13, 1946 2,728,791 Rowlands Dec. 27, 1955 2,741,548 Darling et a1 Apr. 10, 1956 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2956,86) October 18, 1960 Richard J. De Gray I It is hereby certified that error appears in the above numbered pat ent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, lines 2 to 9, and column 4, lines 29 to 34, the formula, each occurrence, should appear-as shown below instead of as in the patent:

r (CH3)2 H l o c l o C Signed and sealed this 9th day of May 1961 (SEAL) Attest:

ERNEST w SWIDER DAVID L, LADD Attesting Officer Commissioner of Patents 

1. THE GASOLINE CONTAINING 0.005 TO 0.1% BY WEIGHT OF AN ORGANIC PHOSPHITE OF THE FORMULA: 